Hack saw blade



Apri 28, `925.

G.J.BLUM

HACK SAW BLADE Original Filed DSC. 8, 1921 @H A n W A i t' mf Q A .-bladeoitrtliis type which is of high eiiiciency Patented Apr. 28, 1925..

UNITED STATES Paisivi GEORGE J. BLUM, or CHICAGO, ILLINOIS, AssIGNoR 'ro THE AnMs'rRONe-BLUM MANU- 'FAO'IURING OOMI'ANY, or CHICAGO, ILLINOIS, A CORPORATION or ILLINOIS.

` HACK SAW BLADE.

I Original' application filed December 8, 1921, Serial No. 520,838. Divided and v September 4, 1923.

To all whom z't may concern;

Beit known that "I, GEORGE J. BLUM, a citizen of `the United' States, residing at Chicago, iii-.the county of Cook and State of Illinoisg'fliave invented ay certain new and useful Hack Saw Blade, of which the fol-z lowing is a specification. 4

The invention relates to cutting blades of.

the' typ'e known -as hacksaw blades; and it has for its general aim the provision of a fipoman'operative standpoint, and at' the i cutting blades, such as hacksaw blades, from solid strips of high speed steel.

^ same time is capable Of-being manufactured at a. relatively low' cost.`

' 'It is common practice` to .construct metalcutting tools from' tungsten steel, commonly known as high speed-steel, it being generally recognized by those skilled in this art that toolsso constructed are-'greatly superior to tools; made Ofcarbon st eel.j Various, attempts have also been made to construct Owing, however, tothe high cost of the material and the increased costof manufacture, it has been found unprofitable, and hence impraci ticable, to manufacture -saw blades as' thus constructed from a solidlstrip of high speed steel., Moreover, suchbla'des'are objection- -able because of their tendency to break or snap'in use. l 4 'The object ofmy invention is tO produce ahacksaw blade possessingallof the advantages of blades constructed wholly of 1 high speed steel, including their durability and their rapid cutting qualities, but having an initial oost approximately onesixth as high as the cost of a blade constructed from a solid strip of high speed ste-el and only slightly in excess of the cost of blades as commonly constructed from carbon steel.

My invention consists in the application under pressure of a narrow strip vof high speed steel tO a strip of ordinary steel having'a low carbon content, while raising the temperature of the two metals at their abut#A ting edges to the fusion point and thus causing them to unite to form an integral structure. The preferred lmethod of manufacture, moreover, involves the rolling'of the strip of high speed steel directly uponone edge'of the strip ofordinary'steel, in a c0ntinnous operation, and while the temperalength.

Serial No. 660,826.

is raised to the fusion'pointby passing electric currents therethrough. The* method thus involves a roll-welding operation, 4whereby the j-oinder of the metals is ef-l this application iled' cisv fected in a progressive mannerfrom one.

end of the blade to the'other. It, therefore,

dili'ers radically from the method common-` ly termed butt-welding, which is capable l of successful usage only'when the abutting edges to be united are of relatively short The 'objects of the invention thus set forth,

together with other and ancillaryl advan-l tion of the parts from which a hacksaw blade is constructed in accordance with my invention, the parts being shown in detached relation. Fig. 2-is a similar vview of the parts after they havevbeen welded together. Fig. 3 is a view of the blade prior to the formation ofthe teeth therein, with astrip of tool steel applied 'to the body or back Ofthe blade so as to form in effect an integral structure. Fig. 4 i-s-a side elevationv Figs. 5 and 6 are of vthe completed blade. fragmentary plan and side views, partially diagrammatic in character, illustrating the methodv employed in the application of the I narrow strip of tool steel to the back or body of the blade.

Referring to Figs'. l, 2 and 5, 7 designates a strip of relatively soft steel from which the bodyor back of the blade is to be formed, and 8 indicates a narrow strip of high speed tool steel of a length substantially equal to that of the strip 7. The dimensions of the strip 8 are such as to render. 1

it exible edgewise.

The strip 8, when applied to the strip 7,

constitutes a cutting edge portion, the-strip i 7 forming the back or body portion. Preferably thel strip 8, while relativelyv thin, Ais

of sutlicieiit thickness to enable -it to be properly ground and ieground if desired, to produce the desired cutting edge.

shown, this cutting` edge isin the form of f saw teeth 9 formed in any suitableY and well.

known way.

Referring now to- Figs. 5

ferred method employed in carrying out my'.

invention consists in the passage of the two stripsgedge to edge between a plurality of 10o As herein rolls, certain of which constitute electrodes arranged so that an electric current passing through the abutting edges of the two strips iaises the temperature thereof to the fusion oint while other rolls press the abutting edges together firmly. In this operation, the two strips are forced bodily together. This occurs as a result of the pressure exerted upon the strips and the condition of the metals when heated. Thus, 'referring to Fig. 6, it will be apparent that as the strip 8 is forced into engagement with the strip 7, the edges of the strips give way slightly and consequently the strip 8 bends outwardly away from the strip 7 above the point of its engagement therewith. Obviously, as the metals become relatively soft or semi-plastic,

. they are merged by the continuous rolling 'may be effected in any suitable way.

operation into an integral structure. This method of applying the cutting edge portion by rolling is also advantageous because it is notlimited to use in connection with straight edges but is capable of use even where the edge to be produced is circular in` form. A

' is that when the'strips are passed between the disks', currents of electricity are caused to .iiw'throu'gh the abuttingedges of the strips, and'from one side thereof to the other. The'electrodes are held, in any suitable way,

Y imposition toengage firmly the-strips 7 and 8,' passing therethrough, fand each is driven by means, not shown, so thatthe desired movement is imparted to the strips.

,12 and 13 designate respectively .rollers engaging the outer edges of the strips 7 l and 8, the-roller 13 exerting under the action of a spring 14 the desired pressure upon the strip 8. A guide block or plate 15 ispreferably stationa-rily mounted with respect to the roll 12. This block has a notchtlierein adapted to receive the outer edge of the strip 7, and thus assists in maintaining the strip in its proper position while passing between the electro( es.

By reason of the rolling pressure exerted upon the strip S in its heatedor semi-plastic condition, it becomes somewhat reduced in width and elongated as shown in Fig. 2.

After the strip 8 is thus initially applied to the strip 7 the united parts are placed in an annealing furnace and treated to facilif tate the work of finishing the blade, the saine being shown in its completed forni, except for the provision of the teeth 9. in Fig. 3. After the teeth have been formed therein and set, the blade is tempered and drawn.

It will be seen that I have produced a cutting blade having all of the advantages of a blade constructed entirely of high speed steel, and yet which is capable of being manufactured at a cost which is not excessive from a practical standpoint. The cutting edge being of high speed steel renders it possible to operate the blade at. a inucli higher rate of speed than is possible with the ordinary blade, and the body er baci: of

'the blade may be made of steel even less expensive than that necessarily employed in the former blade. Also the fact that the cnttiiig edge portion is very narrow, makes it possible toreduce waste in formingthe saine to a minimum. Moreover, my improved blade is superior to that ofthe solid tool steel blade because its back, being made frein relatively softer steel lends toughness and strength to the blade,V thus eliminating largely the tendency of the saine to snap when subjected to extreme strains; and by reason of exceptional durability of the blade, -a substantial saving in labor spent yin replacing wornout blades is effected.y

This application is a division of iny eoendiiig application Serial No. 520588, filed Dec. 8, 1921.

I claim as my invention:

1. A hacksawiblade composed of a thin relatively wide strip of tough steel constituting a back orbody, and a thin relatively narrow strip of high speed steel such as tungsten steel forming a toothed cutting edge of high wearresisting qualities, said strips being arranged in abutting edge relation and welded together so as to be permanently united in an integral blade structure. Y

2. A hacksaw blade composed of a thin relatively wide strip of lowcarbon steel constituting a back or body, and teeth of highV speed steel such as tungsten steel, the back` and teeth being welded together so as to be permanently united .in an integral blade strutture.

In testimony whereof, I have hereunto ailixed my signature.

GEORGE J. BLUM. 

